1. Field of the Invention
The present invention relates to a radiation image detector and a radiation image generating system. In particular, the present invention relates to a radiation image detector and a radiation image generating system each of which is capable of generating an image quickly, saving electric power and realizing a long life duration thereof.
2. Description of Related Art
So far, for a medical diagnosis, a radiation image obtained by irradiating a radiation such as X-ray or the like to a subject and by detecting an intensity distribution of the radiation transmitted through the subject has been widely used. Recently, what has been proposed is a radiation image generating system using an FPD (Flat Panel Detector), which, at the time of generating an image, detects a radiation, converts the detected radiation into electrical signals and accumulates the electrical signals as radiation image information.
What is known as the radiation image generating system, for the purpose of improving flexibility of a system structure, is a system comprising an FPD placed in an image generating room and a predetermined console such as PC (Personal Computer) or the like for performing an image processing, wherein the PC and the FPD are connected through a predetermined communication line (see JP-Tokukai-2003-199726A).
Furthermore, what has been proposed is a system comprising a cassette-type FPD and a console wherein the cassette-type FPD and the console are each other capable of transmitting/receiving various information such as radiation image information or the like, according to a wireless system (for example, see JP-Tokukai-2003-210444A). In the cassette-type FPD, the FPD is contained in a cassette. Therefore, transportability and handling convenience of the FPD are improved, and further flexibility of the system structure is improved.
In view of flexibility improvement, the fact that the cassette-type FPD does not have an obstacle wiring can be cited as one of the characteristics. In this case, the cassette-type FPD incorporates therein a battery charger as an electric power supply source. When the battery charger is consumed to exhaustion of the electric power, the FPD is reused after either charging is performed or a battery is changed.
Therefore, when the electric power is exhausted according to a condition of use or the like, charging needs to be done lots of times in a day, and therefore it is very inconvenient. Further, if the electric power is exhausted when an image is necessary to be generated, what occurs is an inconvenience of not being capable of performing the image generation immediately. Alternatively, when the electric power is exhausted during an image generation, the image generation has to be re-performed. Therefore, there is a possibility of increasing a danger of exposure to the subject. Accordingly, development of a cassette-type FPD which is lightweight and can remain usable for a long time has been necessitated.
Therefore, reduction of wasteful electric power consumption when used has been attempted conventionally. Normally, in an FPD, a power of the radiation image detector is turned on at the beginning of the day, and except for the time of image generation, the FPD is on standby under an image generation standby mode where a voltage is being applied to all the portions that will function after an image is generated, and the power is turned off after the FPD is operated for a whole day so as to be capable of immediately starting generating of an image of a patient except for the time of image generation. At this time, in the FPD, switching between an image generation mode under which image generation is actually performed and the image generation standby mode under which image generation is not actually performed but electric power consumption is smaller than that of the image generation mode and it is possible to immediately start up the FPD to the image generation mode is done, where the switching of each mode is done by attaching/detaching an adapter included in the FPD, as described in JP-Tokukai-2004-141473A. Alternatively, the switching is done by a switch and a timer provided with the FPD as described in JP-Tokukaihei-9-294229A.
As a result, under the standby state where the FPD is not used for image generation, electric power consumption is reduced by not applying a voltage to components to which it is not necessary to apply the voltage on standby, and a time period which is from turning on the power to reaching the state where it is possible to actually perform the image formation, that is, the image generation mode, is reduced. Thereby, electric power saving of the FPD by reducing electric power consumption under the image generation standby mode and immediate transition to the image generation mode have been realized.
However, although electric power consumption amount under the conventional image generation standby mode is smaller than that of the image generation mode, the electric power consumption amount under the conventional image generation standby mode is still larger than that of a state where the power is entirely off. It is very uneconomical especially when only few times of image generation are performed in a day, and therefore it is not sufficient to regard the conventional art as electric power saving.
Further, in order to switch the FPD to the image generation mode immediately, a voltage is for a long time applied to many of the components of the FPD. Thereby, the PD, a TFT and the like are deteriorated, and their sensitivities are decreased. As a result, a life duration of the FPD is shortened despite the fact that the FPD is not actually used very frequently for image generation.
In this way, under the conventional image generation standby mode, it was not possible to realize all of: the immediate transition to the image generation mode; the electric power saving; and the realization of a long life duration, at the same time.